Engineered can body stock and can end stock and methods for making and using same

ABSTRACT

This application discloses aluminum alloy products, such as can body stock and can end stock, that have improved processing qualities in high-speed production equipment due to engineered surfaces. For can body stock, processing is improved by providing at least two different surface roughnesses. For can end stock, processing is improved by reducing anisotropy at least at the top and bottom surfaces of the can end stock.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to and filing benefit of U.S. provisional patent application Ser. No. 62/964,741, filed Jan. 23, 2020, which is incorporated herein by reference in its entirety.

FIELD

The present disclosure is directed to aluminum alloy products and their properties. The disclosure further relates to can body stock, can end stock, and methods of producing and processing the same.

BACKGROUND

Metal cans are well known and widely used as beverage containers. Beverage can bodies are manufactured at high production rates and there is an ever-increasing demand to further increase the production rate of beverage cans by eliminating metal-related jams at the cupper press, as well as tear-offs and split domes at the bodymakers. However, existing aluminum can body stock can cause a reduction in productivity rates for can body production when tension and friction forces are not balanced during the can body production process. In addition, the inherent formability properties of existing anisotropic aluminum can end stock can cause draw-off due to uneven friction forces.

SUMMARY

Covered embodiments of the invention are defined by the claims, not this summary. This summary is a high-level overview of various aspects of the invention and introduces some of the concepts that are further described in the Detailed Description section below. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used in isolation to determine the scope of the claimed subject matter. The subject matter should be understood by reference to appropriate portions of the entire specification, any or all drawings, and each claim.

In one aspect, aluminum alloy products having two different surface roughnesses for use as can body sheet are disclosed herein. The aluminum alloy products can have at least two surfaces, each independently having an average surface roughness that may be abbreviated as Ra. The aluminum alloy products in these examples comprise a first surface having a first average surface roughness and a second surface having a second average surface roughness, wherein the first average surface roughness is at least 20% lower than the second average surface roughness, as measured by a surface profilometer. In some examples, the first average surface roughness is less than 0.4 μm. In some examples, the second average surface roughness is greater than or equal to 0.4 μm.

In some cases, the aluminum alloy is a 3xxx series aluminum alloy, such as an AA3104 aluminum alloy. In some examples, the aluminum alloy comprises about 0.05 — 0.25 wt. % Cu, up to about 0.8 wt. % Fe, about 0.8 — 1.3 wt. % Mg, about 0.8 — 1.4 wt. % Mn, up to about 0.6 wt. % Si, up to about 0.1 wt. % Ti, up to about 0.25 wt. % Zn, up to about 0.05 wt. % impurities, and Al.

In some examples, the aluminum alloy product has a thickness of less than about 4 millimeters (mm).

In a second aspect, methods of making a can body from the can body sheet described above are disclosed herein. The methods of making a can body include contacting the sheet aluminum alloy product with a cupping press to form a cup. The cup comprises a cup inner surface having a cup inner surface average surface roughness and a cup outer surface having a cup outer surface average surface roughness, wherein the cup inner surface average surface roughness is greater than the cup outer surface average surface roughness. The method of making also includes the steps of contacting the cup inner surface with a punch sleeve and contacting the cup outer surface with an ironing die and ironing the cup to a desired height. In some examples, the methods further include trimming the walls to form the can body.

In some examples, the cup has an outer surface average surface roughness Ra (referred to herein as a cup outer surface average surface roughness) that is less than 0.4 μm. In some examples, the cup has an inner surface average surface roughness Ra (referred to herein as a cup inner surface average surface roughness) that is greater than or equal to 0.4 μm. In some instances, the can body has an inner surface having a can body inner surface average surface roughness and an outer surface having a can body outer surface average surface roughness, wherein the can body inner surface average surface roughness is at least 10% greater than the can body outer surface average surface roughness.

In a third aspect, aluminum alloy products for use as can end sheet are disclosed herein. In some examples, the can end sheet has a surface percent isotropy of greater than 80% as measured by confocal microscopy, and has a formability distortion of less than 10%. In some cases, the aluminum alloy product has an isotropy of greater than 95%.

In some examples, the aluminum alloy is a 5xxx series aluminum alloy, for example, a 5182 aluminum alloy. In some examples, the aluminum alloy product has a Texture Aspect Ratio (Str) value of greater than 0.7, according to ISO 25178.

Other objects and advantages of the invention will be apparent from the following detailed description of non-limiting examples.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic drawing of an aluminum alloy cup according to some examples.

FIG. 2 is a schematic drawing of a cross section of an aluminum alloy product according to some examples.

FIG. 3 is a schematic drawing of a stamped can end according to some examples.

DETAILED DESCRIPTION

Described herein are aluminum alloys with improved formability, aluminum alloy products, and methods for making the products. The aluminum alloy compositions and methods described herein provide improved aluminum alloy sheets for the efficient production of aluminum alloy products, such as aluminum can bodies having two different surface roughnesses and can ends having decreased anisotropy.

Definitions and Descriptions:

The terms “invention,” “the invention,” “this invention,” and “the present invention” used herein are intended to refer broadly to all of the subject matter of this patent application and the claims below. Statements containing these terms should be understood not to limit the subject matter described herein or to limit the meaning or scope of the patent claims below.

As used herein, the meaning of “a,” “an,” or “the” includes singular and plural references unless the context clearly dictates otherwise.

In this description, reference is made to alloys identified by aluminum industry designations, such as “series” or “3xxx.” For an understanding of the number designation system most commonly used in naming and identifying aluminum and its alloys, see “International Alloy Designations and Chemical Composition Limits for Wrought Aluminum and Wrought Aluminum Alloys” or “Registration Record of Aluminum Association Alloy Designations and Chemical Compositions Limits for Aluminum Alloys in the Form of Castings and Ingot,” both published by The Aluminum Association.

As used herein, a plate generally has a thickness of greater than about 15 mm. For example, a plate may refer to an aluminum product having a thickness of greater than about 15 mm, greater than about 20 mm, greater than about 25 mm, greater than about 30 mm, greater than about 35 mm, greater than about 40 mm, greater than about 45 mm, greater than about 50 mm, or greater than about 100 mm.

As used herein, a shate (also referred to as a sheet plate) generally has a thickness of from about 4 mm to about 15 mm. For example, a shate may have a thickness of about 4 mm, about 5 mm, about 6 mm, about 7 mm, about 8 mm, about 9 mm, about 10 mm, about 11 mm, about 12 mm, about 13 mm, about 14 mm, or about 15 mm.

As used herein, a sheet generally refers to an aluminum product having a thickness of less than about 4 mm. For example, a sheet may have a thickness of less than about 4 mm, less than about 3 mm, less than about 2 mm, less than about 1 mm, less than about 0.5 mm, less than about 0.3 mm, or less than about 0.1 mm.

As used herein, the term foil indicates an alloy thickness in a range of up to about 0.2 mm (i.e., 200 microns (μm)). For example, a foil may have a thickness of up to 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm, or 200 μm.

All ranges disclosed herein are to be understood to encompass any and all subranges subsumed therein. For example, a stated range of “1 to 10” should be considered to include any and all subranges between (and inclusive of) the minimum value of 1 and the maximum value of 10; that is, all subranges beginning with a minimum value of 1 or more, e.g., 1 to 6.1, and ending with a maximum value of 10 or less, e.g., 5.5 to 10.

The aluminum alloys herein are described in terms of their elemental composition in weight percentage (wt. %) based on the total weight of the alloy. In certain examples of each alloy, the remainder is aluminum, with a maximum wt. % of 0.15% for the sum of the impurities.

Aluminum Can Bodies and Methods of Making the Same

Described herein is an aluminum alloy product for use, for example, as an aluminum can body. The aluminum alloy product can be a sheet that has a substantially planar shape with at least two surfaces, such as a top surface and a bottom surface. “Substantially” planar, for purposes of this application, means having a measurement in the z-axis that is no more than 50%, no more than 40% , no more than 30% , no more than 20% , no more than 10% , no more than 5% ,or no more than 1% of the measurement in either the x axis or the y axis. For example, a sheet that is substantially could have measurements of 1 meter in the x-axis, 1000 meters in the y-axis, and 1 millimeter in the z-axis.

In some examples, the aluminum alloy product is a can body sheet. Differences in the surface roughness of the two sides of the sheet lead to improved processing qualities compared to conventional can body sheet that lacks any substantial difference in surface roughnesses. In other examples, thicker or thinner aluminum alloy products, such as a shate or a foil, respectively, can have different surface roughnesses leading to improved processing characteristics.

The top and bottom surfaces of the aluminum alloy product can have different surface roughnesses Ra, such as a first surface having a first average surface roughness and a second surface having a second average surface roughness. In some cases, the first average surface roughness is at least 20% lower than the second average surface roughness. In other cases, the first average surface roughness is at least 21% lower, at least 22% lower, at least 23% lower, at least 24% lower, at least 25% lower, at least 26% lower, at least 27% lower, at least 28% lower, at least 29% lower, at least 30% lower, at least 35% lower, at least 40% lower, at least 45% lower, at least 50% lower, at least 55% lower, at least 50% lower, at least 65% lower, at least 70% lower, at least 75% lower, at least 80% lower, at least 85% lower, at least 90% lower, or at least 95% lower than the second average surface roughness. For example, if the first side surface roughness is measured and reported as an Ra value, when the Ra value of the second side surface is 1.0 μm, then the maximum surface roughness Ra value of the first surface would be 0.80 μm when the first average surface roughness is at least 20% lower than the second average surface roughness.

Surface roughness may be measured by any method known in the art. In general, a surface profilometer is used to measure and describe the surface features, which is reported as “average surface roughness.” The term average surface roughness is used for purposes herein to convey that the surface features may be regular and repeating in a consistent manner, like the surface features of an egg carton, or irregular and not repeating in a consistent manner, like the surface of a mountain range. In general, the “average surface roughness” measures and reports the average distance from a plane. For example, a two dimensional (2D) or a three dimensional (3D) profilometer may be used to determine average surface roughness. In some cases, the profilometer employs a stylus to measure average surface roughness; in other cases, optical methods may be used. A person of ordinary skill will understand that even though one particular method may be specified, any method capable of detecting a difference in the average roughness of two different surfaces may be used, and the difference between the two measurements may be expressed as a percentage. In some examples, the average surface roughness is measured by confocal microscopy. The surfaces are characterized herein by various parameters, including Ra and Rz, which are measured in micrometers (microns) and are known to those of skill in the art. Optionally, the parameters can be measured using the MountainsMap® Surface Imaging and Metrology software (Digital Surf; Besancon, France). All roughness values can be mechanically measured with a standard stylus. In other examples, the average surface roughness is measured and reported as Str according to ISO 25178 [2019]. The Str value is the ratio of the shortest wavelength to the longest wavelength measured in any direction relative to the rolling direction.

During the production of can bodies, such as beverage can bodies, a can body sheet is subjected to two-piece drawing and wall ironing. The can body sheet is first contacted with a cupping press to form a cup, and then the cup is transferred to a punch sleeve for drawing and ironing. As shown in FIG. 1 , the cup 10 has an inner surface 11 and an outer surface 12.

During drawing and ironing, it is necessary to balance the friction between the punch sleeve and the inner surface of the cup with the tension between the ironing dies and the outer surface of the cup. Not intending to be bound by theory, when tension and friction are balanced, fractures are reduced. Traditional methods of balancing tension and friction involve adding a lubricant to the outer surface that contacts the ironing die. With the materials and processes disclosed herein, rather than reducing tension between the outer surface of the cup and the ironing die (e.g., by using additional lubricant), the friction between the punch sleeve and the cup inner surface is increased by having a rougher surface in contact with the punch sleeve, with the smoother outer surface in contact with the ironing die. Thus, the materials and methods disclosed herein have the advantages of reducing can body fractures and also reducing the amount of lubricant. Although the materials and methods are described in some instances regarding can body sheet, a person of ordinary skill will understand that the materials and methods are applicable to any aluminum alloy product that is punched, stamped, drawn and/or ironed, when it would be beneficial to increase friction between a machine component and a surface of an aluminum alloy product. Thus, the aluminum alloy product can be a shate, a sheet, or a foil. Further, the person of ordinary skill will understand that the average surface roughnesses required to balance tension and friction, as well as the difference between the two average surface roughnesses required, may vary according to the particular design of the punch sleeves and the ironing dies and the particular aluminum alloy product.

In some examples, the first surface, which may correspond to the outer surface 12 of the cup 10, is smoother than the second surface, which may correspond to the inner surface 11 of the cup 10. In this way, the first average surface roughness Ra of the first surface is lower than the second average surface roughness Ra of the second surface. A smoother surface will have fewer and/or smaller topographical features such as bumps, ridges, lines, and/or projections than a rougher surface. In some examples, the first average surface roughness Ra is less than 0.4 μm. In other examples, the first average surface roughness Ra is less than 0.38 μm, less than 0.36 μm, less than 0.34 μm, less than 0.32 μm, less than 0.28 μm, less than 0.26 μm, less than 0.24 μm, less than 0.22 μm, less than 0.2 μm, less than 0.18 μm, less than 0.16 μm, less than 0.14 μm, less than 0.12 μm, less than 0.1 μm, less than 0.08 μm, less than 0.06 μm, less than 0.04 μm, less than 0.02 μm, or less than 0.01 μm.

In some examples, the second average surface roughness Ra is greater than or equal to 0.4 μm. In other examples, the second average surface roughness Ra is greater than or equal to 0.6 μm, greater than or equal to 0.8 μm, greater than or equal to 1.0 μm, greater than or equal to 1.5 μm, greater than or equal to 2 μm, greater than or equal to 2.5 μm, greater than or equal to 3 μm, greater than or equal to 3.5 μm, greater than or equal to 4 μm, greater than or equal to 4.5 μm, greater than or equal to 5 μm, greater than or equal to 5.5 μm, greater than or equal to 6 μm, greater than or equal to 6.5 μm, greater than or equal to 7 μm, greater than or equal to 7.5 μm, greater than or equal to 8 μm, greater than or equal to 8.5 μm, greater than or equal to 9 μm, greater than or equal to 9.5 μm, greater than or equal to 10 μm, or greater than or equal to 15 μm.

In another aspect, methods of making aluminum can bodies are described herein. The methods of making a can body comprise the steps of contacting an aluminum alloy product having two different surface roughnesses with a cupping press to form a cup comprising a cup inner surface having a cup inner surface average surface roughness and a cup outer surface having a cup outer surface average surface roughness, wherein the inner surface average surface roughness is greater than the outer surface average surface roughness; contacting the cup inner surface with a punch sleeve and contacting the cup outer surface with an ironing die; and ironing the cup to a desired height. Because the rougher surface of the aluminum alloy product is in contact with the punch sleeve, friction between the punch sleeve and the rougher surface balances the tension between the ironing die and the smoother surface. In some examples, the methods further comprise the step of trimming the walls to form the can body.

Any of the aluminum alloy products (such as a shate, a sheet, or a foil) described above may be used, as long as the aluminum alloy product has a difference in roughness of two of its sides. In some examples, the outer surface average surface roughness Ra of the cup is less than 0.4 μm. In other examples, the outer surface average surface roughness Ra is less than 0.38 μm, less than 0.36 μm, less than 0.34 μm, less than 0.32 μm, less than 0.3 μm, less than 0.28 μm, less than 0.26 μm, less than 0.24 μm, less than 0.22 μm, less than 0.2 μm, less than 0.18 μm, less than 0.16 μm, less than 0.14 μm, less than 0.12 μm, less than 0.1 μm, less than 0.08 μm, less than 0.06 μm, less than 0.04 μm, less than 0.02 μm, or less than 0.01 μm.

In some examples, the inner surface average surface roughness of the cup Ra is greater than or equal to 0.4 μm. In other examples, the inner surface average surface Ra is greater than or equal to 0.45 μm, greater than or equal to 0.5 μm, greater than or equal to 0.6 μm, greater than or equal to 0.8 μm, greater than or equal to 1.0 μm, greater than or equal to 1.5 μm, greater than or equal to 2 μm, greater than or equal to 2.5 μm, greater than or equal to 3 μm, greater than or equal to 3.5 μm, greater than or equal to 4 μm, greater than or equal to 4.5 μm, greater than or equal to 5 μm, greater than or equal to 5.5 μm, greater than or equal to 6 μm, greater than or equal to 6.5 μm, greater than or equal to 7 μm, greater than or equal to 7.5 μm, greater than or equal to 8 μm, greater than or equal to 8.5 μm, greater than or equal to 9 μm, greater than or equal to 9.5 μm, greater than or equal to 10 μm, or greater than or equal to 15 μm.

Can bodies manufactured using the products and methods described herein differ from a conventional can body in that at least a portion of the can body inner surface has an average surface roughness that is greater than the average surface roughness of the can body outer surface. Thus, in some examples, the can body comprises an inner surface having a can body inner surface average surface roughness and an outer surface having a can body outer surface average surface roughness, where the can body inner surface average surface roughness is at least 20% greater than the can body outer surface average surface roughness. In other cases, the can body inner surface average surface roughness is at least 22% greater, at least 24% greater, at least 25% greater, at least 26% greater, at least 28% greater, at least 30% greater, at least 35% greater, at least 40% greater, at least 45% greater, at least 50% greater, at least 55% greater, at least 60% greater, at least 65% greater, at least 70% greater, at least 75% greater, at least 80% greater, at least 85% greater, at least 90% greater, or at least 95% greater than the can body outer surface average surface roughness.

The aluminum alloy products and methods described herein can be used for preparing beverage cans, food containers, or any other desired application. In some examples, the aluminum alloy products and methods can be used to prepare beverage can bodies.

Aluminum alloys for use in the products and methods described herein include 3xxx series aluminum alloys. Suitable 3xxx series aluminum alloys include, for example, AA3002, AA3102, AA3003, AA3103, AA3103A, AA3103B, AA3203, AA3403, AA3004, AA3004A, AA3104, AA3204, AA3304, AA3005, AA3005A, AA3105, AA3105A, AA3105B, AA3007, AA3107, AA3207, AA3207A, AA3307, AA3009, AA3010, AA3110, AA3011, AA3012, AA3012A, AA3013, AA3014, AA3015, AA3016, AA3017, AA3019, AA3020, AA3021, AA3025, AA3026, AA3030, AA3130, and AA3065. μm. In some examples, the aluminum alloy is AA3104.

In some examples, the alloys for use in the products and methods described herein can have the following elemental composition as provided in Table 1.

TABLE 1 Element Weight Percentage (wt. %) Cu 0.05-0.4    Fe 0-0.9 Mg 0.8-3.0   Mn 0.8-2.0   Si 0-0.7 Ti 0-0.1 Zn  0-0.25 Cr 0-0.4 Others 0-0.05 (each) 0-0.15 (total) Al Remainder

In some examples, the alloy can have the following elemental composition as provided in Table 2.

TABLE 2 Element Weight Percentage (wt. %) Cu 0.05-0.25 Fe   0-0.8 Mg 0.8-1.3 Mn 0.8-1.4 Si   0-0.6 Ti   0-0.1 Zn    0-0.25 Others 0-0.05 (each) 0-0.15 (total) Al Remainder

In some examples, the aluminum alloy comprises 0.05-0.4 wt. % Cu, up to about 0.9 wt. % Fe, about 0.8-3.0 wt. % Mg, about 0.8-2.0 wt. % Mn, up to about 0.7 wt. % Si, up to about 0.1 wt. % Ti, up to about 0.25 wt. % Zn, up to about 0.15 wt. % impurities, and Al.

In some examples, the aluminum alloy comprises 0.05-0.25 wt. % Cu, up to about 0.8 wt. % Fe, about 0.8-2.8 wt. % Mg, about 0.8-1.4 wt. % Mn, up to about 0.6 wt. % Si, up to about 0.1 wt. % Ti, up to about 0.25 wt. % Zn, up to about 0.15 wt. % impurities, and Al.

In some examples, the aluminum alloy comprises 0.05-0.3 wt. % Cu, about 0.4 -about 0.8 wt. % Fe, about 0.8-2.8 wt. % Mg, about 0.1-1.5 wt. % Mn, about 0.25-0.6 wt. % Si, up to about 0.1 wt. % Ti, about 0.1-0.25 wt. % Zn, up to about 0.35 wt. % Cr, up to about 0.15 wt. % impurities, and Al.

In some examples, the alloys described herein include copper (Cu) in an amount of from about 0.05% to about 0.40% (e.g., from about 0.05% to about 0.35% or from about 0.10% to about 0.30%) based on the total weight of the alloy. For example, the alloy can include 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.10%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.20%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, 0.30%, 0.31%, 0.32%, 0.33%, 0.34%, 0.35%, 0.36%, 0.37%, 0.38%, 0.39%, or 0.40% Cu. All are expressed in wt. %.

In some examples, the alloys described herein include iron (Fe) in an amount of up to about 0.9% (e.g., from about 0.3% to about 0.85% or from about 0.4% to about 0.8%) based on the total weight of the alloy. For example, the alloy can include 0%, 0.05%, 0.10%, 0.15%, 0.20%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, 0.30%, 0.31%, 0.32%, 0.33%, 0.34%, 0.35%, 0.36%, 0.37%, 0.38%, 0.39%, 0.40%, 0.41%, 0.42%, 0.43%, 0.44%, 0.45%, 0.46%, 0.47%, 0.48%, 0.49%, 0.5%, 0.51%, 0.52%, 0.53%, 0.54%, 0.55%, 0.56%, 0.57%, 0.58%, 0.59%, 0.6%, 0.61%, 0.62%, 0.63%, 0.64%, 0.65%, 0.66%, 0.67%, 0.68%, 0.69%, 0.7%, 0.71%, 0.72%, 0.73%, 0.74%, 0.75%, 0.76%, 0.77%, 0.78%, 0.79%, 0.8%, 0.81%, 0.82%, 0.83%, 0.84%, 0.85%, 0.86%, 0.87%, 0.88%, 0.89%, or 0.9% Fe. In some cases, Fe is not present in the alloy (i.e., 0%).All are expressed in wt. %.

In some examples, the alloys described herein include magnesium (Mg) in an amount of from about 0.8% to about 3.0% (e.g., from about 0.8% to about 2.8% or from about 1.0% to about 2.5%) based on the total weight of the alloy. For example , the alloy can include 0.8%, 0.81%, 0.82%, 0.83%, 0.84%, 0.85%, 0.86%, 0.87%, 0.88%, 0.89%, 0.9%, 0.91%, 0.92%, 0.93%, 0.94%, 0.95%, 0.96%, 0.97%, 0.98%, 0.99%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, or 3.0% Mg. All are expressed in wt. %.

In some examples, the alloys described herein include manganese (Mn) in an amount of from about 0.1% to about 2.0% (e.g., from about 0.1% to about 1.5% or from about 0.5% to about 1.5%) based on the total weight of the alloy. For example, the alloy can include 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.2%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, 0.3%, 0.31%, 0.32%, 033%, 0.34%, 0.35%, 0.36%, 0.37%, 0.38%, 0.39%, 0.4%, 0.41%, 0.42%, 0.43%, 0.44%, 0.45%, 0.46%, 0.47%, 0.48%, 0.49%, 0.5%, 0.51%, 0.52%, 0.53%, 0.54%, 0.55%, 0.56%, 0.57%, 0.58%, 0.59%, 0.6%, 0.61%, 0.62%, 0.63%, 0.64%, 0.65%, 0.66%, 0.67%, 0.68%, 0.69%, 0.7%, 0.71%, 0.72%, 0.73%, 0.74%, 0.75%, 0.76%, 0.77%, 0.78%, 0.79%, 0.8%, 0.81%, 0.82%, 0.83%, 0.84%, 0.85%, 0.86%, 0.87%, 0.88%, 0.89%, 0.9%, 0.91%, 0.92%, 0.93%, 0.94%, 0.95%, 0.96%, 0.97%, 0.98%, 0.99%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, or 2.0% Mn. All are expressed in wt. %.

In some examples, the alloys described herein include silicon (Si) in an amount of up to about 0.7% (e.g., from about 0.25% to about 0.6% or from about 0.3% to about 0.55%) based on the total weight of the alloy. For example, the alloy can include 0%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.2%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, 0.3%, 0.31%, 0.32%, 0.33%, 0.34%, 0.35%, 0.36%, 0.37%, 0.38%, 0.39%, 0.4%, 0.41%, 0.42%, 0.43%, 0.44%, 0.45%, 0.46%, 0.47%, 0.48%, 0.49%, 0.5%, 0.51%, 0.52%, 0.53%, 0.54%, 0.55%, 0.56%, 0.57%, 0.58%, 0.59%, 0.6%, 0.61%, 0.62%, 0.63%, 0.64%, 0.65%, 0.66%, 0.67%, 0.68%, 0.69%, or 0.7% Si. In some cases, Si is not present in the alloy (i.e., 0%). All are expressed in wt. %.

In some examples, the alloys described herein include titanium (Ti) in an amount up to about 0.1% (e.g., from about 0.01% to about 0.08% or from about 0.02% to about 0.05%) based on the total weight of the alloy. For example, the alloy can include 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, or 0.1% Ti. In some cases, Ti is not present in the alloy (i.e., 0%). All are expressed in wt. %.

In some examples, the alloys described herein include zinc (Zn) in an amount up to about 0.25% (e.g., from about 0.01% to about 0.25% or from about 0.1% to about 0.2%) based on the total weight of the alloy. For example, the alloy can include 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.2%, 0.21%, 0.22%, 0.23%, 0.24%, or 0.25% Zn. In some cases, Zn is not present in the alloy (i.e., 0%). All are expressed in wt. %.

In some examples, the alloys described herein include chromium (Cr) in an amount up to about 0.4% (e.g., from about 0.01% to about 0.35% or from about 0.05% to about 0.3%) based on the total weight of the alloy. For example, the alloy can include 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.2%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, 0.3%, 0.31%, 0.32%, 0.33%, 0.34%, 0.35%, 0.36%, 0.37%, 0.38%, 0.39%, or 0.4% Cr. In some cases, Cr is not present in the alloy (i.e., 0%). All are expressed in wt. %.

Optionally, the alloy compositions described herein can further include other minor elements, sometimes referred to as impurities, in amounts of 0.05% or below, 0.04% or below, 0.03% or below, 0.02% or below, or 0.01% or below. These impurities may include, but are not limited to Zr, Sn, Ga, Ca, Bi, Na, Pb, or combinations thereof. Accordingly, Zr, Sn, Ga, Ca, Bi, Na, or Pb may be present in alloys in amounts of 0.05% or below, 0.04% or below, 0.03% or below, 0.02% or below or 0.01% or below. In some cases, the sum of all impurities does not exceed 0.15% (e.g., 0.10%). All are expressed in wt. %. The remaining percentage of the alloy is aluminum.

Aluminum Can Ends and Methods of Making the Same

Also described herein is an aluminum alloy product for use, for example, as can end stock. The can end stock described herein has surfaces that are substantially isotropic, and exhibits improved formability over the standard can end stock having an anisotropic “directional” surface, referred to herein as the standard directional material. The increased formability of the can end stock described herein is due, at least in part, to its increased surface isotropy as compared to the standard directional material. “Substantially” isotropic, for purposes of this application, means having at least 70%, at least 75%, at least 80%, at least 85%, or at least 95% isotropy.

The aluminum alloy products described herein are less prone to issues resulting from low formability, such as product cracking, particularly during a punching operation on a shell press. Not to be bound by theory, this is due, in part, to the fact that in the standard directional material, the friction in the direction 90° to the rolling direction is highest. In the standard directional material, the forming loads are increased due to direct impingement from the topographical peaks created with a standard roll ground surface. In the products described herein, however, the number of peaks is lowered by at least 10% as compared to the standard directional material. For example, the number of peaks can be lowered by at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90% as compared to the standard directional material. In some cases, no peaks are present. Thus, the friction is balanced in all directions and the extreme loads from friction at the 90° component are lowered. Moreover, when a circular product, such as a can end, is formed from standard directional material, the resulting shape is not a perfect circle, but is “off-drawn” into a subtle elliptical shape with the largest diameter being in the 90° direction. This is a direct result of the higher friction (and hence higher forming load) in the 90° direction. The operating window for forming can be widened with the surfaces described herein to manage the “off-drawn” phenomena.

The surface isotropy of the aluminum alloy product may be increased by any known method, such as nanosecond laser micro texturing, electrodischarge texturing, or rolling with a modified a work roll or rolling in the cross direction. It is not necessary to change the metallurgical properties (including directionality or anisotropy) of the center portion of the aluminum alloy product that result from the rolled production process; rather, benefits are present when the outer surface isotropy is increased.

Processing is improved by reducing anisotropy at least at the top and bottom surfaces of the can end stock, whether or not some residual anisotropy remains in the center portion between the top and bottom surfaces of the can end stock. Thus, in some examples, the aluminum alloy product comprises a thickness having a top portion, a center portion, and a bottom portion. In some examples, the top and bottom portions comprise 0.1% of the thickness of the aluminum alloy product. For example, an aluminum alloy product may have a thickness of 200 μm; when the top and bottom portions comprise 1% of the thickness, they together measure 2 μm, leaving the measurement of the center portion at 198 μm. In some examples, the top and bottom portions comprise 0.5% of the thickness, 1% of the thickness, 5% of the thickness, 10% of the thickness, 15% of the thickness, 20% of the thickness, or 25% of the thickness. In some examples, the top and bottom portions are of equal measurement; in other cases, the top and bottom portions are not of equal measurement. As shown in FIG. 2 , a cross-section of an aluminum alloy product 20 comprises a top portion 21, a center portion 22, and a bottom portion 23.

In some examples, the aluminum alloy product has a surface percent isotropy of greater than 80% as measured by confocal microscopy, and has a formability distortion of less than 10%. “Surface percent isotropy” for the purposes of this application refers to isotropy as measured on a surface (top and/or bottom) of the aluminum alloy product, even if the isotropy of the aluminum alloy product varies through the thickness of the aluminum alloy product. In some examples, the aluminum alloy product comprises a surface percent isotropy of greater than 85%, greater than 90%, greater than 95%, greater than 97%, greater than 98%, greater than 99%, or 100%.

“Formability distortion” for purposes of this application refers to the maximum off-drawn when an aluminum alloy product is stamped with a circular die, such as on a shelling press, expressed as a percent of the radius of the circle. For example, when a circle is stamped using a die with a 2.5 cm diameter, and the stamped product is a perfect 2.5 cm diameter circle, the formability distortion is zero. However, if the stamped product has a radius at one or more points that exceeds the intended 2.5 cm diameter, then the formability distortion is nonzero. If the maximum radius in this example is 2.75 cm, then the formability distortion is 10 percent. ((2.75-2.50/2.5) =0.10, or 10%). In some examples, the formability distortion is less than 9%, less than 8%, less than 7%, less than 6%, less than 5%, less than 4%, less than 3%, less than 2%, less than 1%, or zero. As shown in FIG. 3 , a stamped can end 30 may be off-drawn from a perfect circle, shown in dotted line. The maximum radius 31 is larger than the circle radius 32.

The aluminum alloy products useful for can end stock described herein can have any suitable gauge. In some examples, the aluminum alloy product can be a sheet. The sheet can be used as can end stock.

In some examples, the aluminum alloy product is a sheet such as a can end sheet. In some examples, the aluminum alloy is a 5xxx series aluminum alloy. Suitable 5xxx series aluminum alloys include, for example, AA5005, AA5005A, AA5205, AA5305, AA5505, AA5605, AA5006, AA5106, AA5010, AA5110, AA5110A, AA5210, AA5310, AA5016, AA5017, AA5018, AA5018A, AA5019, AA5019A, AA5119, AA5119A, AA5021, AA5022, AA5023, AA5024, AA5026, AA5027, AA5028, AA5040, AA5140, AA5041, AA5042, AA5043, AA5049, AA5149, AA5249, AA5349, AA5449, AA5449A, AA5050, AA5050A, AA5050C, AA5150, AA5051, AA5051A, AA5151, AA5251, AA5251A, AA5351, AA5451, AA5052, AA5252, AA5352, AA5154, AA5154A, AA5154B, AA5154C, AA5254, AA5354, AA5454, AA5554, AA5654, AA5654A, AA5754, AA5854, AA5954, AA5056, AA5356, AA5356A, AA5456, AA5456A, AA5456B, AA5556, AA5556A, AA5556B, AA5556C, AA5257, AA5457, AA5557, AA5657, AA5058, AA5059, AA5070, AA5180, AA5180A, AA5082, AA5182, AA5083, AA5183, AA5183A, AA5283, AA5283A, AA5283B, AA5383, AA5483, AA5086, AA5186, AA5087, AA5187, and AA5088. μm. In some examples, the aluminum alloy comprises a 5182 aluminum alloy.

The anisotropy of the surface can be measured by the Texture Aspect Ratio (Str), according to ISO 25178, as described above. The Str value is the ratio of the shortest wavelength to the longest wavelength measured in any direction relative to the rolling direction. In some examples, the Str value for the surface of alloy sheet as described herein is greater than about 0.7. For example, the Str value can be 0.71, 0.75, 0.8, 0.85, 0.9, 0.95, 0.96, 0.97, 0.98, 0.99 or 1.0. Conventional aluminum alloy sheets used to prepare can end stock, however, typically have an anisotropic surface texture. The Str value for the surface of a conventional alloy sheet is less than 0.1. The anisotropic nature of conventional can end stock can cause formability issues, such as split domes and tear offs. The aluminum alloy products useful for can end stock described herein are free of significant anisotropy.

Illustrations of Suitable Alloys, Products, and Methods

Illustration 1 is an aluminum alloy product, comprising a first surface having a first average surface roughness; and a second surface having a second average surface roughness, wherein the first average surface roughness is at least 20% lower than the second average surface roughness, as measured by a surface profilometer.

Illustration 2 is the aluminum alloy of any preceding or subsequent illustration, wherein the first average surface roughness is at least 30% lower than the second average surface roughness. Illustration 3 is the aluminum alloy of any preceding or subsequent illustration, wherein the first average surface roughness is less than 0.4

Illustration 4 is the aluminum alloy of any preceding or subsequent illustration, wherein the second average surface roughness is greater than or equal to 0.4

Illustration 5 is the aluminum alloy of any preceding or subsequent illustration, wherein the aluminum alloy product comprises a 3xxx series aluminum alloy.

Illustration 6 is the aluminum alloy of any preceding or subsequent illustration, wherein the 3xxx series aluminum alloy comprises an AA3104 aluminum alloy.

Illustration 7 is the aluminum alloy of any preceding or subsequent illustration, wherein the aluminum alloy product comprises about 0.05-0.25 wt. % Cu, up to about 0.8 wt. % Fe, about 0.8-1.3 wt. % Mg, about 0.8-1.4 wt. % Mn, up to about 0.6 wt. % Si, up to about 0.1 wt. % Ti, up to about 0.25 wt. % Zn, up to about 0.05 wt. % impurities, and Al.

Illustration 8 is the aluminum alloy of any preceding or subsequent illustration, wherein the aluminum alloy product comprises a thickness of less than about 4 mm. Illustration 9 is the aluminum alloy of any preceding or subsequent illustration, wherein the aluminum alloy product is an aluminum can body.

Illustration 10 is a method of making an aluminum can body, comprising contacting the aluminum alloy product of claim 1 with a cupping press to form a cup comprising a cup inner surface corresponding to the second surface and having a cup inner surface average surface roughness and a cup outer surface corresponding to the first surface and having a cup outer surface average surface roughness, wherein the cup inner surface average surface roughness is greater than the cup outer surface average surface roughness; contacting the cup inner surface with a punch sleeve and contacting the cup outer surface with an ironing die; and ironing the cup to a desired height.

Illustration 11 is the method of any preceding or subsequent illustration, wherein the cup has walls and the method further comprises trimming the walls to form the can body, wherein the can body has a can body inner surface and a can body outer surface. Illustration 12 is the method of any preceding or subsequent illustration, wherein the cup outer surface average surface roughness is less than 0.4 μm.

Illustration 13 is the method of any preceding or subsequent illustration, wherein the cup inner surface average surface roughness is greater than or equal to 0.4 μm.

Illustration 14 is the method of any preceding or subsequent illustration, wherein the aluminum can body comprises an inner surface having a can body inner surface average surface roughness and an outer surface having a can body outer surface average surface roughness, wherein can body inner surface average surface roughness is at least 20% greater than the can body outer surface average surface roughness.

Illustration 15 is an aluminum alloy product comprising a surface percent isotropy of greater than 80% as measured by confocal microscopy, and comprising a formability distortion of less than 10%.

Illustration 16 is the aluminum alloy of any preceding or subsequent illustration, wherein the aluminum alloy product comprises an isotropy of greater than 95%.

Illustration 17 is the aluminum alloy of any preceding or subsequent illustration, wherein the aluminum alloy product comprises a 5xxx series aluminum alloy.

Illustration 18 is the aluminum alloy of any preceding or subsequent illustration, wherein the 5xxx series aluminum alloy comprises a 5182 aluminum alloy.

Illustration 19 is the aluminum alloy of any preceding or subsequent illustration, wherein the aluminum alloy product is an aluminum can end.

Illustration 20 is the aluminum alloy of any preceding or subsequent illustration, wherein the aluminum alloy product comprises a Texture Aspect Ratio (Str) value of greater than 0.7, according to ISO 25178.

All patents, publications and abstracts cited above are incorporated herein by reference in their entirety. Various embodiments of the invention have been described in fulfillment of the various objectives of the invention. It should be recognized that these embodiments are merely illustrative of the principles of the present invention. Numerous modifications and adaptations thereof will be readily apparent to those skilled in the art without departing from the spirit and scope of the present invention as defined in the following claims. 

1. An aluminum alloy product, comprising: a first surface having a first average surface roughness; and a second surface having a second average surface roughness, wherein the first average surface roughness is at least 20% lower than the second average surface roughness, as measured by a surface profilometer.
 2. The aluminum alloy product of claim 1, wherein the first average surface roughness is at least 30% lower than the second average surface roughness.
 3. The aluminum alloy product of claim 1, wherein the first average surface roughness is less than 0.4 μm.
 4. The aluminum alloy product of claim 1, wherein the second average surface roughness is greater than or equal to 0.4 μm.
 5. The aluminum alloy product of claim 1, wherein the aluminum alloy product comprises a 3xxx series aluminum alloy.
 6. The aluminum alloy product of claim 5, wherein the 3xxx series aluminum alloy comprises an AA3104 aluminum alloy.
 7. The aluminum alloy product of claim 1, wherein the aluminum alloy product comprises 0.05-0.25 wt. % Cu, up to 0.8 wt. % Fe, 0.8-1.3 wt. % Mg, 0.8-1.4 wt. % Mn, up to 0.6 wt. % Si, up to 0.1 wt. % Ti, up to 0.25 wt. % Zn, up to 0.05 wt. % impurities, and Al.
 8. The aluminum alloy product of any claim 1, wherein the aluminum alloy product comprises a thickness of less than about 4 mm.
 9. The aluminum alloy product of claim 1, wherein the aluminum alloy product is an aluminum can body.
 10. A method of making an aluminum can body, comprising: contacting the aluminum alloy product of claim 1 with a cupping press to form a cup comprising a cup inner surface corresponding to the second surface and having a cup inner surface average surface roughness and a cup outer surface corresponding to the first surface and having a cup outer surface average surface roughness, wherein the cup inner surface average surface roughness is greater than the cup outer surface average surface roughness; contacting the cup inner surface with a punch sleeve and contacting the cup outer surface with an ironing die; and ironing the cup to a desired height.
 11. The method of claim 10, wherein the cup has walls and the method further comprises trimming the walls to form the can body, wherein the can body has a can body inner surface and a can body outer surface.
 12. The method of claim 10 or 11, wherein the cup outer surface average surface roughness is less than 0.4 μm.
 13. The method of claim 10, wherein the cup inner surface average surface roughness is greater than or equal to 0.4 μm.
 14. The method of claim 11, wherein the aluminum can body comprises an inner surface having a can body inner surface average surface roughness and an outer surface having a can body outer surface average surface roughness, wherein the can body inner surface average surface roughness is at least 20% greater than the can body outer surface average surface roughness.
 15. An aluminum alloy product comprising a surface percent isotropy of greater than 80% as measured by confocal microscopy, and comprising a formability distortion of less than 10%.
 16. The aluminum alloy product of claim 15, wherein the aluminum alloy product comprises an isotropy of greater than 95%.
 17. The aluminum alloy product of claim 15, wherein the aluminum alloy product comprises a 5xxx series aluminum alloy.
 18. The aluminum alloy product of claim 17, wherein the 5xxx series aluminum alloy comprises a 5182 aluminum alloy.
 19. The aluminum alloy product of claim 15, wherein the aluminum alloy product is an aluminum can end.
 20. The aluminum alloy product of claim 15, wherein the aluminum alloy product comprises a Texture Aspect Ratio (Str) value of greater than 0.7, according to ISO
 25178. 